1. Field of the Invention
The present invention relates to a device and a method for generating a plurality of different kinds of timing signals, e.g., control signals for controllably driving a solid-state image pickup device, timing signals for a signal processing circuit, and control signals for periodically controlling various circuits.
2. Description of the Background Art
Today, an image pickup apparatus of the type including a solid-state image pickup device is extensively used. The image pickup device outputs an image signal derived from an optical image, which is representative of a scene incident thereto. The image signal is processed and then recorded in a data recording medium or transmitted to another apparatus, as desired. A controller organically controls a shooting section, a signal processing section, a recording section and other sections constituting the apparatus. A timing signal generating device, or so-called timing generator, generates timing signals that define the operation timings of the various sections of the apparatus.
Japanese patent laid-open publication No. 257398/1998, for example, discloses a generator for generating timing signal which drives a solid-state image pickup device and capable of outputting programmable pulses ø. The generator includes a plurality of frequency dividers for dividing a clock. A selector selects divided clocks output from the frequency dividers in accordance with selection data. A counter counts clocks selected. A decoder decodes clocks output from the counter in accordance with a decode value. Control means sets the data selected and decoded values. The data selected and decoded values are set via a serial port. The problem with this type of device is that data setting effected via a serial line is time-consuming and therefore slows down the operation of the entire system including the device.
Various kinds of solid-state image pickup devices have recently been developed and applied to digital cameras. Various shooting functions are available with a digital camera using a solid-stated image pickup device. For example, the image pickup device is driven at a timing which differs from a still picture to a moving picture, and is sometimes driven in such a manner as to reduce, or thin, pixels to be read out. Such different driving methods each need particular timing signals. Moreover, an image signal output from the image pickup device is subjected to various kinds of signal processing including analog signal processing, digitization, and digital signal processing that processes pixel-by-pixel digital data. For each of such signal processing, particular timing signals must be fed to a particular section of the camera.
To implement multiple functions described above, a great amount of data defining various timings must be set in a signal generating device, consuming a long period of time. As a result, a system including a signal generating device, which can be loaded with data, needs an extra data setting time. For example, substantial part of a start-up time after the power-up of the system must be allocated to data setting, degrading the performance of the entire system.